1.Cut off root ends and dark green parts of leeks and slice them down the middle. Wash leeks thoroughly and slice them thinly. You should have 6 cups of white and pale green sliced leeks. Set them aside.

2.Peel potatoes and cut them into small chunks. Add to leeks.

3.Melt margarine in soup pot over medium high heat. Add leeks and potatoes and stir well. Saute vegetables until leeks have softened. Add five cups of broth. Bring to a boil, reduce to a simmer and cover pot. Simmer vegetables 12-15 minutes or until they are very tender. Remove cover.

4.Rinse spinach and watercress well and add to soup pot. Stir 2-3 minutes until they are wilted but still bright green. Cool about 15 minutes.

5.Insert steel blade into bowl of processor. Puree soup two cups at a time. (I like to have a few lumps of potatoes left so that everyone gets a little surprise in their bowl.) Pour pureed soup into large bowl. Stir in lemon juice. Add pepper to taste. Chill soup until it is very cold. Add one more cup of broth if you want a thinner consistency. Taste again and adjust seasoning- even adding more lemon juice if you like.